(1) Field of the Invention
The present invention relates to a microwave oven, and more particularly, to a choke printed circuit board including a choke means mounted thereon, which is provided in the electric component compartment.
(2) Description of the Prior Art
Generally, a microwave oven is a cooking appliance which cooks food by frictional heat generated by making the molecules of the food being cooked move at high speeds utilizing high frequency energy. FIG. 3 illustrates the inner structure of a prior art microwave oven.
As shown in the figure, the microwave oven includes a housing 10 which consists of an inner case 12 and an outer case 11, and a cooking chamber 20 and an electric component compartment 40 which are isolated from each other by the inner case 12 for forming the cooking chamber 20 and the outer case 11. On the front side of the inner case 12 is rotatably mounted a door 30 to open and close the cooking chamber 20 and is attached a control panel 31i ncluding a display and several operating buttons. The electric component compartment 40 is provided in the space formed between the inner case 12 and the outer case 11. In the electric component compartment 40 are mounted a magnetron 41 for creating microwaves and emitting them to the cooking chamber 20, a guide duct 44 for guiding air drawn into the electric component compartment 40 to the cooking chamber 20 through the intake holes 45 formed on the side plate of the inner case 12, a high-voltage transformer 42 for applying high voltage to the magnetron 41, and a cooling fan 43 for cooling the electric components.
The cooling fan 43 is mounted in the center of the motor bracket 47 which is attached to the inner side of the rear plate enclosing the electric component compartment 40. On the top of the motor bracket 47 is mounted a choke printed circuit board 46 (hereinafter called choke PCB) which includes a choke means 46 a for eliminating noises included in the input power and a fuse 46 b to protect the electric components in the electric component compartment 40.
The choke means 46a and fuse 46b being uncovered in the electric component compartment 40 can have damaging, and possibly dangerous, results: When the cooling fan 43 operates, air is heat-exchanged with the magnetron 41, directed to the cooking chamber 20, and then discharged outside. At this time, a portion of the air passing through the microwave oven re-enters the electronic component compartment 40. Accordingly, moisture is generated in the electric component compartment 40 due to the temperature difference between the re-entered air and newly entered air. If it contacts the choke means 46a or the fuse 46b, which are exposed in the electric component compartment 40, a short circuit may be caused, thereby resulting in damage to the machine and a possible fire hazard. Furthermore, when a repair man inspects or repairs the microwave oven after disassembling the outer case 11, he may receive an electric shock by contacting the choke means 46a or the fuse 46b charged with electricity. Lastly, because the top surface of the exposed choke PCB 46 becomes covered with dust, the parts on the choke PCB 46 may not function properly.